1. Field of the Invention
The present invention relates to a displacement sensor which utilizes an optical cutting method to measure a displacement of an object.
2. Description of the Related Art
Conventionally, there are known sensor devices for measuring the displacement, a length, and an angle of various measurement objects. For example, a conventional displacement sensor includes a floodlighting unit, a light acceptance unit, calculation means, and output means. The floodlighting unit irradiates a measurement object with a line beam by driving a floodlighting element such as a laser diode. The light acceptance unit accepts slit light which is reflected by the measurement object after emitted from the floodlighting unit. The calculation means calculates a distance to the measurement object. The output means outputs the distance to the measurement object, which is calculated by the calculation means (refer to, for example, Japanese Patent No. 3599239).
The conventional displacement sensor can measure a sectional outline shape irradiated with the line beam on the measurement object. The use of the conventional displacement sensor can check whether or not a product falls within a specification range in a production line. Generally, in the case of a product inspection, a determination is seldom made by comparing a whole shape of a product to be inspected to that of a good product from the viewpoints of hardware necessary for processing and a processing time. However, the inspection is performed by measurements of a position and a height of a point which becomes important in the shape and a distance between the points. For example, in the case where the height and depth of a step are measured, a user separately sets an area including a step surface used in calculating the step from the sectional outline shape by a user. Which height and depth are measured from a reference position in the sectional outline shape is set by the area even in a top and bottom measurement instead of the step. In the case of the measurement of a step edge position on the measurement object, the area including the step edge position is set to perform the measurement.
However, in the conventional displacement sensor, a place which the user measures is specified and set in each time when a measurement process is performed based on plural local regions or feature points. Therefore, a setting operation is obscure and setting work is troublesome.